With developing display panel technology, a display panel with narrow border and high resolution is more and more popular among customers. In order to meet the demand of customers, higher accuracy of a black matrix affecting resolution and size of display panel is also needed. Nowadays, the procedure of manufacturing a black matrix is usually performed by using scanning exposure method and proximity exposure method. Wherein, the accuracy of scanning exposure method is higher, and the manufacturing cost is higher because the expense is more expensive; as a result, most enterprise choses proximity exposure method. However, the structure of a mask plate by using proximity exposure method, transparent region—shading region, makes exposed photoresist directly contacts with non-exposed photoresist, and then affects dimensional accuracy of the photoresist because it is difficult to control time during developing procedure; therefore, dimensional accuracy of the black matrix pattern made by using proximity exposure method will be lower.